CRM_Contact_BAO_Contact_Utils::generateChecksum($mailing->id, NULL, NULL, NULL, 'mailing', 16);
$groupTableName = CRM_Contact_BAO_Group::getTableName();
CRM_Contact_BAO_Contact_Utils::generateChecksum($mailing->id, NULL, NULL, NULL, 'mailing', 16);
$groupTableName = CRM_Contact_BAO_Group::getTableName();